The disclosures herein relate generally to mounting bracket assemblies. More particularly, the disclosures herein relate to vibration damping mounting bracket assemblies for system components in a computer.
Some system components, such as high performance hard drives, require rigid mounting to the chassis of a computer system to achieve optimum performance. The servo tracking performance of a hard drive is hindered by displacement of the disk drive unit in response to inertial forces associated with movement of the head actuator arms. Reducing, or preferably, eliminating movement of the disk drive body relative to the chassis of the computer system allows a desired string of data to be read from the disk drive more readily and accurately.
The force associated with mounting the disk drive against a rigid surface in a high-speed computer assembly operation can result in high G-load impacts. If the impact is great enough, one or more of the heads in the disk drive may experience an impact-induced head crash. An impact-induced head crash occurs when one or more of the heads in the disk drive collide against the surface of an adjacent disk. A head crash may damage the head or the disk, resulting in reduced performance and reliability. The damage may result in immediate failure or undetected damage leading to a shortened operating life.
Conventional mounting techniques associated with high performance hard disk drives result in undesired levels of audible acoustic noise emitted from the hard disk drive. The cost associated with technical support calls and field replacements relating to acoustic noise adversely affects profitability and productivity. Furthermore, an increasing number of customers have implemented a side-by-side comparison of competing products when making purchasing decisions. In such cases, excess acoustic noise can become an obstacle to attracting the business of certain customers.
U.S. Pat. No. 5,706,168 discloses a portable personal computer configured for rugged use. The computer has an impact attenuating case, a sealed keyboard, and a sealed mouse which facilitate use of the computer in harsh environments. The case has an impact attenuating covering. A hard drive is housed in the case on resilient grommets, reducing impact induced shock and acoustic noise.
U.S. Pat. No. 5,463,527 discloses a disk drive support system including a disk drive suspended within a sleeve-like support housing. The disk drive is suspended from two upper corners and two lower corners using four elastomeric mounts bridging the drive and housing at each corner. Each mount has one zone affixed to the drive and another opposite zone affixed to the housing by tangs on the drive and housing which engage two respective slots in the mount. Shock absorber pads are provided on the disk drive which are separated from the housing by an air space so as to absorb shocks but not transmit vibrations. The two upper elastomeric mounts are of a higher durometer hardness than the two lower elastomeric mounts.
U.S. Pat. No. 5,149,048 discloses a shock absorbent jacket for mounting a disk drive or other component in a computer. The jacket is received in a cavity or recess in a computer. The cavity is sized and shaped in such a way that the jacket is loosely held between the surface of the component and the inner surface of the cavity. The cavity itself may be completely enclosed, or it may have various openings. For example, it may take the form of a cage or lattice arrangement on one or more sides. It is essential, however, that the surfaces which define the cavity be positioned so that they function cooperatively with the shock absorbent jacket to protect the disk drive or other component from shocks in any direction.
It is known in the industry that vibration associated with rotating parts within a hard drive is a significant source of noise generated by a hard disk drive. Mounting devices for damping vibrations often require a significant amount of additional space. In many computers such as workstations, space is very limited. As a result, the space and mounting requirements preclude many conventional vibration damping solutions from being used.
Accordingly, what is needed is a system component mounting apparatus that absorbs vibrations, that attenuates acoustical noise, that meets the mounting requirements of high performance system components, and that can be used in applications with limited space.